Faecalibacterium prausnitzii is one of the most abundant bacteria in the human gut microbiota. This bacterium is reported to serve an important role in inflammatory bowel diseases. In the present study, the preventive effects of F. prausnitzii on a dextran sodium sulfate (DSS)‑induced colitis model in mice were investigated. BALB/c mice were fed with 5% DSS in drinking water. Administration of live or inactivated F. prausnitzii was initiated 7 days prior to the start of DSS feeding. Mucosal cytokines were analyzed by reverse transcription‑quantitative PCR. Histological analysis of colon mucosa was also performed. The symptoms of DSS‑induced colitis (weight loss, diarrhea, bloody stools and colon shortening) were significantly improved in the group administered live F. prausnitzii, but not in the other groups. There were no significant differences in the expression of proinflammatory cytokines; however, the expression of mucosal cytokines appeared to be markedly reduced in the live F. prausnitzii‑administered group compared with the DSS‑fed control. The results suggested that preventive administration of 'live', but not inactivated, F. prausnitzii protected the colon against DSS‑induced colitis. Live F. prausnitzii were also administered therapeutically following the induction of colitis, resulting in an improved histological score in mice.